Geogebra at WIU

This is a page of notes I created to help myself, my students, and the teachers I work with learn and use Geogebra.  

Geogebra is a dynamic geometry and algebra program. Geogebra is open-source, free, and easy-to-use!  You can run it in the browser or download it to your machine and run it without Internet access.  Geogebra will be revolutionary in the way I use technology to teach mathematics. 

Math 505 with McKinley

Getting Started                                                                                                          Videos Below

• First big key: To construct something:  Click what you want on the toolbar at the top first, then hover over the tool to see what you need to click to make it happen (or click the question mark icon). (In the previous versions you read to the right of the buttons what needs to be selected to make it happen).  (This is the "non-selection" paradigm!  With many programs (including GSP), you have to pre-select points/objects and then click the command.  With Geogebra you click the command first.)
•  Second big key: Use the selection pointer to click and drag points. Click the far left (arrow) button or press Esc to get the selection pointer. 
• Third big key: Right-click Properties and experiment.  You can learn most everything you need.
• Fourth big key: The input (command) line at the bottom of the screen is where you can type commands.  You may type the command or you can select the command from the list of choices.  To get the proper syntax/inputs you can click F1.

With those four keys, you can do most things by experimenting.  I've written a few more notes below for reference.  You may also want to look at GeoGebra Quickstart - 8-page pdf.

More Notes

• Mathematics is done using the toolbar.  E.g., plotting points, measuring segments, graphing functions.
• The menus do not do any mathematics.  The menus only change appearance - how things look (e.g., font for text). 
• You can do a lot with right-click -- including properties.
• When you save, the filename is ---.ggb

• The regions of the screen are: (control what you view with the View menu)

• Graphics view (where the points and graphics are)
• Algebra view on the left side which lists all the objects.  Note: you can hide (or show) an object easily by clicking it's "bullet" in the Algebra view.
• Input Bar (command line) at the bottom.
• Spreadsheet view - which is optional.

• Did I mention Right-click Properties and experiment?

• I often like to only have it show labels of new points (not label segments, circles, etc.).  To do this click Options|Labeling|New Points Only.  Then, you can click  Options|Save Settings.

• Edit|Properties is useful (because it shows all objects) for:
• Recovering hidden text
• Editing properties of objects not in the Algebra Window.
• Finding names of objects, because objects are organized differently than the Algebra Window.
• The Help screens are good.

Going Further

• Points can be shown as open circles or dots of various sizes by using properties|style (of the point).
• To create text boxes and labels you can do it two ways.
• Use Insert Text which is under the second tool from the right.
• Use Text[] in the command line.  E.g., Text[x(A)] and position (under properties|position) it to a point
• There are keyboard shortcuts - see help for a list.
• When things are created using the input line they are still free objects.
• Functions.  In the command line type f(x)=x^2+3 to create a function.
•  Piece-wise defined/Boolean: 
• f(x) = If[x < 3, sin(x), x^2] gives you a function that equals sin(x) for

  x < 3 and x² for x ≥ 3.      g(x) = If[x < 3, sin(x)] is also legal.  (Of course, you can nested If's.)

• The other way to do this is to use the function (sorry) Function[Function, Number a, Number b]: Yields a function graph, that is equal to f on the interval [a, b] and not defined outside of [a, b].

  Note: This command should be used only in order to display functions in a certain interval. 

  Example: f(x) = Function[x^2, -1, 1] gives you the graph of function x² in the interval [-1, 1].

Note: g(x)=1*f(x) "reinstates" f (any multiple will do this)  (see function commands in help)

• Control+F is refresh (also clears a trace)
• You can create indices within the names of objects by using an underscore. For example A₁ is entered as A_1 and s_AB is entered as s_{AB}.
• Use uppercase for points.  Use lowercase for vectors.
• Sliders are pretty easy to create.

Videos

This is just an Introduction to Geogebra - Some Nice Features.  Shows some of the power of Geogebra.  Click here (opens in new window).  (by Jim O.)

Getting Started with Geogebra - 1st of 2 videos.  Shows three of the keys to using Geogebra. Click here (opens in new window).  (by Jim O.)

Getting Started with Geogebra - 2nd of 2 videos.  Shows three of the keys to using Geogebra. Click here (opens in new window).  (by Jim O.)

http://math247.pbworks.com/Learn-and-Use-GeoGebra - more details on GeoGebra.

Nice Things Geogebra Does 

• Geogebra does many things from many branches of mathematics, including derivatives. 
• Geogebra 4 now has a CAS (Computer Algebra System).
• You can show a tangent to a function!  Use the Tangent command.
• There is a Slope command (slope of a line) shows little right triangle.
• Geogebra does statistics too!

Page created by Jim Olsen, Western Illinois University.

Please e-mail suggestions, corrections, or additions to this page JR-Olsen "at" wiu.edu.

This PBWorks page is open to the public.

URL: http://geogebraatwiu.pbworks.com/